Furnace skid rails



1957 J. M. GUTHRIE 3,34

FURNACE SKID RAILS Filed Aug. 25, 1965 4 Sheets-Sheet.1

INVENTOR. JAMES M. eumma.

51%;; aka MU ATTOR NEYS- J. M. GUTHRIE Oct. 3, 1967 FURNACE SKID RAILS 4Sheets-Sheet 2 I Filed Aug. 25, 1965 INVENTOR. JAM E5 M. GUTHRIE.

ATTORNEYS.

Oct. 13,1967 J. M. GUTHRIE 3,345,050

FURNACE SKID RAILS Filed Aug. 25, 1965 4 Sheets-Sheet 3 INVENTOR. JAMESM.6UTHRIE.

BY may M Md MAZ ATTORNEYS.

Oct. 3, 1967 J. M. GUTHRIE 3,345,050

FURNACE SKIID RAILS Filed Aug. 25, 1965 4 Sheets-Sheet 4 INVENTOR. JAMESM. GUTHRIE.

at; M aha/M ATTORNEYS.

United States Patent 3,345,050 FURNACE SKID RAILS James M. Guthrie,Crafton, Pa., assignor to Loftus Engineering Corporation, a corporationof Maryland Filed Aug. 25, 1965, Ser. No. 482,405 13 Claims. (Cl. 263-6)ABSTRACT OF THE DISCLOSURE This disclosure relates to fuel-firedfurnaces, known as continuous or pusher type furnaces, in which steelslabs, blooms, billets, ingots, or other forms of metal articles areheated to rolling, forging or other desired temperature. One row, ormore, of such articles is supported on water-cooled skid rails extendingbetween the charging end of the furnace and a refractory soaking ordischarge hearth located adjacent to the opposite end of the furnace.The articles to be heated are mechanically pushed intermittently intothe charging end of the furnace, causing the row of articlescorrespondingly to advance to discharge position on the soaking hearth.In their sojourn in the furnace the articles are heated to desiredtemperature, except those portions of the articles in contact with theskid rails. Those portions are at a lower temperature than the remainderof the articles, forming what are known in the art as skid marks, whichcannot be removed during the time the articles are thermally soaked onthe discharge hearth, at least not without the articles dwelling on thehearth for so long a time as to reduce the production of the furnace toa prohibitive degree. In order to reduce the cooling effect of the skidrails on the engaged body portions of the metal articles, novel meansare combined with the skid rails to arrest or diminish the thermalconductivity between such rails and the bodies of the articles supportedthereby.

My present invention relates to continuous or pushertype furnaces forheating slabs, ingots, billets, or like heavy articles of metal, to beheated for rolling, forging, or other shaping operation.

More particularly, the invention is concerned with the water-cooledskids that support the articles to be advanced step by step through thefurnace and heated to working temperature during their sojourn in thefurnace.

Hitherto, the problem in operating such furnaces is to eliminate skidmarks in the heated articles discharged from the furnace, skid marksbeing darker colored regions in the heated articles which, due tocontact with the water-cooled skids, are at lower temperature than therest of the bodies of the articles. These skid marks or regions of lowertemperature in a heated article to be rolled, or otherwise shaped,prevent or impair the obtainment of a uniform product. It has been thepractice in the art to provide a soaking hearth in the furnace, on whichhearth the heated articles are allowed to dwell in the hopes that theskid marks will be soaked out; that is, the entire body of each heatedarticle will be brought to uniform temperature. The latter practice hasproved to be of some benefit, but the results have never been completelysatisfactory, since, if the heated articles are allowed to soak longenough to completely remove the skid marks, the production of thefurnace is curtailed to an impractical or economically prohibitivedegree.

The object of my invention is to provide a solution of this problem;that is, to provide a skid construction which will inhibit orsubstantially eliminate skid marks, while maintaining optimum productionrates of the furnace. An ancillary object is to provide thermalinsulation for the water-cooled skids whereby the skids will 3,345,050Patented Oct. 3-, 196-7 be protected against furnace heat, or, otherwiseexpressed, the amount of furnace heat lost or dissipated by thewater-cooling of the skids will be minimized.

The invention will be understood upon reference to the accompanyingdrawings, in which:

FIG. 1 is a view in central longitudinal section of a pusher-typefurnace in which my invention is useful;

FIG. 2 is a fragmentary isometric view illustrating features of theinvention;

FIG. 3 is a fragmentary view, showing in side elevation a certainwater-cooled header used in securing and supporting the water-cooledpipes of which my improved skids are constructed;

FIG. 4 is a view in plan from above of the structure shown in FIG. 3; a

FIG. 5 is a sectional view of the latter structure, as seen on the planeV-V of FIG. 4;

FIG. 6 is a fragmentary sectional view of the structure, as seen on theplane VIVI of FIG. 3;

FIG. 7 is a view of the header structure, as seen from the right of FIG.3, but omitting certain refractory blocks and refractory rail elements;

FIG. 8 is a view in cross-section, showing a pair of water-cooled pipesin cross-section, and illustrating a modification in the form of therefractory blocks that are of double utility; they support therefractory rail elements and thermally insulate the pair of water-cooledp p FIG. is a view similar to FIG. 8, but showing a single Water-cooledpipe as the support for the refractory blocks and refractory railelements;

FIG. 10 is a view in cross-section of a pair of watercooled pipes,similar to the showing of FIG. 8, but illustrating that each refractorysupporting block may be formed in one piece rather than in two;

FIG. 11 is a view corresponding to FIG. 9 of a single water-cooled pipearranged within refractory supporting and insulating blocks of integralconstruction; and

FIG. 12 is a view in cross-section of a single watercooled pipe havingrefractory blocks .of bipartite construction suspended from the pipe forthe purpose of insulating the water-cooled pipe from furnace heat.

Referring to FIG. 1 of the drawings, a furnace of the sort in which theimprovements of my invention are particularly advantageous is indicatedgenerally at 1. In this case the furnace is designed to heat slabs S ofsteel as they are successively advanced step by step through apreheating section 2, a heating section 3, and a soaking section 4.Extending longitudinally from the charging doorway 5 of the furnace tothe soaking hearth 6 are laterally spaced skids 7, and below these skidsa system of burners 8 directs burning columns of fluid fuel andcombustion air for heating the slabs from beneath, while a system ofburners 9 functions to heat the slabs from above, in the course of theirtravel through furnace heating sections 2 and 3.

The slabs S are carried to the charging end of the furnace on a rollertable 10, whence they are pushed in required sequence over a chargingplatform 11, through the furnace charging door 5 and upon the skids 7.The pusher mechanism for this purpose is well-known in the art,wherefore such mechanism is not shown herein. During normal furnaceoperation, one or more lines of slabs extend continuously from thecharging door to the dis charge knuckle 12 of the soaking hearth. Thesoaking zone is fired from above by means of system of burners 13. Whenit is desired to deliver a slab from the furnace, a cold slab is pushedthrough charging door 5 into the furnace; this advances the entire lineof slabs by a distance approximately equal to the width of the enteringslab, with the consequence that the end slab on the soak ing hearthfalls to the discharge slope 14 and slides to a 3 roller table 15 thatpropels the heated slab to a rolling \mill. The foregoing generaldescription of the pushertype furnace illustrated herein will sufficefor this specification, and attention will now be directed specificallyto the improvements wherein my invention is found.

The entire skid structure 7 may be constructed throughout its lengthbetween the charging door 5 and the soaking hearth 6 in such way that noskid marks occur in the slabs S, with the consequence and effect thatthe soaking hearth may be economically constructed in shorter lengththan it normally is. Conceivably in some instances, by virtue of myinvention, the soaking hearth may be substantially eliminated, withsubstantial savings in the cost of the furnace. In the present case,however, I prefer that the skid structure 7 may be of conventionalconstruction, except in the reach of the structure between point 16 inthe furnace and the soaking hearth 6, and it is in this reach the skidmarks imparted to the slabs S between the charging door 5 and point 16will, due to the skid structure described below, be removed before theslabs reach the soaking hearth.

Referring to FIG. 2 of the drawings, it will be understood that thereare two or more parallel skid structures 7 laterally spaced across thewidth of the furnace 1. Each skid structure in its extent between thecharging end 5 of the furnace and the point 16 (FIG. 1) may be ofconventional construction, formed as a beam of extra heavy steel pipe17. The steel pipe is anchored in usual way to the foundation of theslab-pushing mechanism (not shown) adjacent to the charging end of thefurnace, and/or to the adjacent foundation and structural steel bindingof the furnace itself. At its opposite or inner end (cf. point 16,FIG. 1) each reach of pipe 17 is secured, as by welding, to a hollowwater-cooled header 18 formed of steel. On the top of each skid pipe 17,and throughout the effective length thereof, a steel wearing bar 19 iswelded (FIG. 2), and it is on the wearing bars 19 of the four skidstructures shown that the slabs S rest; that is, those slabs S of thatportion of the row which extends between the charging door 5 and point16 in the furnace.

In the reach of the skid structure between the point 16 in the furnaceand the soaking hearth 6, two laterally spaced extra heavy pipes 20, 20(FIGS. 2 to 7) extend in parallelism from each header 18 to a header 21(FIG. 1) adjacent to the soaking hearth 6. The paired pipes 20, 20 arewelded at their opposite ends to the headers 18 and 21, respectively,and the interiors of the pipes stand in open communication with theinteriors of the hollow headers 18 and 21.

Means are provided for laterally and vertically supporting the skidpipes 17 and 20, 20, whereby the great weight of the slabs S may besustained by such pipes. Such means comprise extra heavy steel crosspipes 22 on which the said skid pipes rest, and cross pipes 23 thatextend through and are welded to the headers 18 and 21. The cross pipes22 and 23 extend through the opposite side walls of the furnace and areunited with the heavy steel buckstays on the outside of the furnace. Themanner in which the cross pipe 23 shown in FIG. 2 is supported, as at24, to the buckstays 24a of the furnace binding will suffice for anunderstanding of the structural organization of all cross pipes 22 and23 to provide lateral support for the longitudinal skid pipes 17 and 20,20 of the furnace. The main vertical support for the skid pipes isprovided by means of heavy steel stanchion pipes 25a that bear the crosspipes 22 and stanchion pipes 25 that bear the headers 18 and 21.

The stanchion pipes 24 and 25 extend downwardly through the hearth ofthe furnace and are secured to the steel hearth-supporting beams 26, asindicated at 27 in FIG. 2.

In FIGS. 1 and 2 of the drawings the hollow watercooled headers 18 and21 are shown of simple cubical construction, but in FIGS. 3 to 6 theheaders are shown to be of more refined design, each including seats 28for the ends of pipes 17 and 20, 20 welded to the headers, and a socket28a for engaging the top of a stanchion pipe 25. And as shown in FIG.5,-each header is provided with an internal cylindrical wall 29, forminga cylindrical passage through which a lateral pipe 23 may extend topermit a circulation of cooling water in such pipe independently of thecooling water circulating through the headers and skid pipes. Each ofthe stanchion pipes 25a and 25 has a stream of cooling water deliveredupwardly into it by a feeder pipe 29 (FIG. 2) that extends almost to thetop of the stanchion pipes, and the stream of cooling water flowsdownwardly between the walls of the stanchion pipe and its feeder pipe29, whence it exits into any suitable drain.

It is important to note that the paired skid pipes 20, 20 are verticallyoffset below the horizontal plane of skid pipes 17 (FIGS. 3 and 7), thedesign of the headers 18 and 21 providing an excellent structuralaccommodation for this feature. On each pair of skid pipes 20, 20 aseries of-refractory saddle blocks 30 is supported, such blocks beingarranged in close relation, while providing for such slight movementrelative to one another as is occasioned by the flexing of the pipes 20,20 under the weight of the slabs S as they are pushed through thefurnace. The body of each saddle block is provided with seat portions 31that snugly engage the skid pipes 20, 20 (FIG. 6), and the body portionof each block above the seats 31 form a bearing that includes a recess33. The recesses in the aligned blocks 30 provide a channel in which asuccession of refractory slab-engaging elements 32 is contained. Theseelements 32 transmit the weight or load of the slabs to the saddleblocks 30. For convenience in expression these members 32 may be termedrefractory rail or wearing elements. The top surfaces of the railelements 32 lie in the horizontal plane of the top edge of theassociated rail element 19 that extends between the charging door 5 andpoint 16 in the furnace. The refractory rail elements 32 may be formedof a fused-cast refractory material such as silicon carbide, or of anelectrically cast alumina composition available on the open market underthe name Monofrax.

It will be noted that the bodies of refractory blocks 30 includeportions 35, 35 and 36 (FIG. 6) that form open-bottomed slots 37, 37which, when each block is seated on the pipes 20, 20 are closed byrefractory disks 38, 38 slipped into place and secured in slots 39. Byvirtue of the downwardly extending refractory block portions 35, 35, 36and disks 38, 38 together with the body portions of the blocks above therails, the skid pipes 20, 20 are enveloped by the refractory blocks,wherefore such blocks serve as saddles to support the rail elements 32and also serve as themal insulation for the water-cooled pipes 20, 20,protecting the pipes from furnace heat and minimizing the quantity ofheat which is withdrawn by the pipes from the furnace and dissipated. Itwill be noted that each refractory rail element 32 is supported in thealigned channels 33 of a plurality of adjacent blocks 30three blocks inthis case. In order to minimize any tendency for the rail elements tofracture or crack under the weight of the slabs S pushed over them, ametal shoe 40 (FIG. 6) of a heat-resisting steel is inserted endwise inthe channels 33 of the blocks 30. Each shoe 40 may be equal in lengthwith the rail element 32 it supports.

The tops of the headers 18 are provided with integral metal railportions 34 that bridge the space between the ends of wearing bars 19 onskid pipes 17 and the adjacent ends of the lines of refractory railelements 32 borne by blocks 30 and skid pipes 20, 20, as shown in FIG.2. Similarly, the headers 21 may be provided with rail elements 34 andthe slab-bearing top surface of soaking hearth 6.

Thus, a water-cooled skid structure may be provided to meet the aims ofthis invention.

Referring to FIG. 8, the refractory saddle blocks 30 may be of bipartiteconstruction, each including an upper half 30a and a lower half 30b. Theskid pipes 20a, 20a are provided with hanger clips 41, upon which thelower block sections 30b may be engaged, as by means of complementaryslots in the block sections 30b, and tongue and groove joints 42 may beprovided in the two halves of each block, to assist in maintainingalignment of the halves, and to circumvent infiltration of furnace fumesor gases between the halves. The upper or load-bearing section 30a ofeach block may include a recess 33a, to provide with adjacent blocksections 30a a channel to receive the refractory rail elements 32a, withor without alloy shoes 40a.

FIG. 9 illustrates that in some cases a single watercooled skid pipe 20bmay serve in lieu of the paired skid pipes 20, 20 and that the lowersection 300 of each bipartite refractory block may be secured by asingle T-shaped hanger clip 41a welded to the skid pipe and engaged in asuitable slot in each block section 30c.

FIG. 10 serves to indicate, by way of a further modification thatmonolithic refractory saddle blocks 30d may be threaded on the pairedskid pipes 200, 200 before such pipes are welded at their opposite endsto the headers 18 and 21 (FIG. 1).

In the event a single water-cooled skid pipe 20d is used, monolithicblocks 30e may be threaded on the pipe before it is Welded to theheaders 18 and 21. A keeper bar 43 of steel may be welded to the pipe,and a corresponding slot in each block 30c cooperates to insure that allof the blocks in the series of blocks on the pipe will remain in desiredalignment.

In the case of the skid pipes that extend between the charging door andpoint 16 of the furnace, it is desirable thermally to insulate the pipe.FIG. 12 illustrates in cross-section such a skid pipe at 17a, equippedwith a steel wearing rail 19a. For this purpose bipartite blocks 30f,30] of refractory or insulating material may be suspended on the pipe,by means of T-clips 44 welded to the pipe and engaged in complementaryslots formed in the block sections.

In the case of the clips 41 of FIG. 8, the clips 41a of FIG. 9, and theclips 44 of FIG. 12, it will be understood that such clips comprise analigned series of spaced-apart clips that extend longitudinally of thewater-cooled skid pipes to which they are welded, with the spacesbetween successive clips of suflicient scope to permit the lower halvesof the refractory blocks in each case to be raised between the adjacentclips and inched along the pipe into suspended positions on the adjacentclips. The lower half of the last block in the series extending betweenthe headers 18 and 21 may be molded in situ of a suitable plasticrefractory material.

The skid construction between the point 16 and the soaking hearth 6 ofthe furnace may be applied to the load-supporting beams of walking beamfurnaces of well-known design, in which the water-cooled steel pipes ofcircular cross-section may comprise one or more water-cooled pipes orhollow water-cooled steel beams of rectangular or other cross-section,such steel beams being considered the mechanical equivalent of circularpipes or beams.

Within the terms of the appended claims other modifications andvariations in the skid pipe structure described may be made withoutdeparting from the spirit of the invention.

I claim:

1. A skid structure for supporting metal articles to be heated, saidskid structure comprising two reaches of water-cooled pipe arranged inlongitudinal succession between the charging and discharging ends of thefurnace, the water-cooled pipe of the reach closer to the charging endof the furnace having a metal wearing rail secured on its top, thewater-cooled pipe of the second reach having a line of refractory railelements and means for support- 6. ing them on the latter pipe withtheir top surfaces aligned with the top surface of said wearing rail,the water-cooled pipe of the second reach extending in a horizontalplane that is substantially parallel to but lower than the plane of thewater-cooled pipe of said first reach, water-cooled means for unitingthe adjacent ends of the pipes of said vertically offset reaches, andwater-cooled supports for vertically and laterally supporting saidwater-cooled means and the reaches of water-cooled pipe.

2. A skid structure for supporting metal articles to be heated in apusher-type furnace, said skid structure comprising a substantiallyhorizontal pair of laterally spaced parallel water-cooled pipes, twowater-cooled headers severally secured to the opposite ends of saidpipes, a water-cooled jack vertically supporting each header,water-cooled lateral braces extending outwardly from the opposite sidesof each header, a row of closely arranged refractory blocks havingload-bearing portions seated on said pair of pipes between said headers,and refractory rail elements borne by said blocks for slideablysupporting the metal articles to be heated in said furnace.

3. The structure of claim 2, wherein the seated blocks have bodies thatextend downwardly over the bodies of said water-cooled pipes, wherebysaid blocks provide both a support for said rail elements and a thermalinsulation for the pipes against furnace heat.

4. The structure of claim 2, wherein the bodies of said blocks includetwo slots with open lower ends that receive said water-cooled pipes whenthe blocks are moved into seated positions on the pipes, and refractoryportions engaged to said blocks for closing the lower ends of said slotswhen the blocks have been seated, whereby said blocks provide both asupport for said rail elements and a thermal insulation of the saidpipes from furnace heat.

5. The structure of claim 2, wherein said refractory rail elements spana plurality of said refractory railelement-bearing blocks seated on thepipes between said headers, together with a metal shoe interposedbetween each refractory rail element and the plurality of refractoryblocks that bear the rail element.

6. The structure of claim 2, wherein said closely ar ranged refractoryblocks seated on said pair of pipes include refractory portions whichenvelop said pipes from below, whereby said refractory blocks provideboth a seat for said refractory rail elements and a thermal insulationfor the supporting pipes from furnace heat.

7. The structure of claim 2, wherein said refractory rail elements spana plurality of said refractory rail-elementbearing blocks seated on thepipes between said headers, together with a metal shoe interposedbetween each refractory rail element and the plurality of refractoryblocks that bear the rail element, said rail-element-bearing blocksseated on the pipes between said headers having refractory portionswhich envelop said pipes from below, whereby the refractory blocksprovide both a seat for each refractory rail element and a thermalinsulation for the supporting pipes from furnace heat.

8. A skid structure for supporting metal articles to be heated in apusher-type furnace, said skid structure comprising two reaches ofwater-cooled pipe arranged in longitudinal succession between thecharging and discharging ends of the furnace, the water-cooled pipe ofthe reach closer to the charging end of the furnace having a metalwearing rail secured on its top, the watercooled pipe of the secondreach having a line refractory rail elements and means for supportingthem on the latter pipe with their top surfaces aligned with the topsurface of said wearing rail, the water-cooled pipe of the second reachextending in a horizontal plane that is substantially parallel to butlower than the plane of the water-cooled pipe of said first reach, awater-cooled header uniting the adjacent ends of the pipes of saidvertically offset reaches, and water-cooled means for vertically andlaterally supporting said header and the reaches of water-cooled pipe,

the means for supporting the line of refractory rail elements of saidsecond reach comprising a closely arranged series of refractory blockshaving load-bearing portions seated on and extending along said secondreach of pipe.

9. The structure of claim 2, said refractory blocks having portions thatcooperate with said load-bearing portions to insulate the water-cooledpipe of the second reach from furnace heat.

10. A skid structure for supporting metal articles to be heated in apusher-type furnace, said skid structure comprising a reach ofwater-cooled pipe anchored at one end adjacent to the charging end ofthe furnace and extending in a generally horizontal direction toward thedischarge end of the furnace, at water-cooled header united to theopposite end of said pipe, a pair of spaced parallel water-cooled pipesunited with said header and extending therefrom toward the discharge endof the furnace in a plane vertically offset below the plane of thefirst-named water-cooled pipe, means for vertically and laterallysupporting said header and the pipes united thereto, said first-namedWater-cooled pipe having a metal wearing rail secured on its top, saidvertically offset pair of pipes having a series of closely arrangedrefractory blocks seated thereon to form a saddle, and a line ofrefractory rail elements seated in the saddle formed by said blocks,with the tops of said rail elements in substantial alignment with thetop of said metal wearing rail on the firstnamed pipe.

11. The structure of claim 10, said refractory saddle blocks havingbodies that substantially envelope said vertically offset pair of pipes,whereby the blocks provide 8 both a support for said refractory railelements and a thermal insulation for the pipes.

12. The structure of claim 10, wherein said refractory rail elementseach span a plurality of said refractory saddle blocks, together with ametal shoe interposed between each refractory rail element and thebodies of the refractory blocks that bear the rail element.

13. A parallel pair of water-cooled skid pipes for supporting articlesto be heated in a pusher-type furnace, said skid pipes having hangermeans secured thereto, a series of closely arranged refractory blocks,each of said blocks having two separate body portions, one of said bodyportions having two seats for severally engaging said pipes from above,and the other of said body portions being suspended from said pipes bysaid hanger means, the two body portions so assembled with the pair ofskid pipes providing means for both supporting a refractory rail elementand for thermally insulating the pair of pipes.

References Cited UNITED STATES PATENTS 1,262,794 4/1918 Hofmann 263-62,295,474 9/1942 Horn 263-6 3,169,754 2/1965 OReilly 2636 3,214,15210/1965 Molz 2636 3,226,101 12/1965 Balaz et a1. 2636 FREDERICK L.MATTESON, J,R., Primary Examiner.

JOHN J. CAMBY, Examiner.

2. A SKID STRUCTURE FOR SUPPORTING METAL ARTICLES TO BE HEATED IN APUSHER-TYPE FURNACE, SAID SKID STRUCTURE COMPRISING A SUBSTANTIALLYHORIZONTAL PAIR OF LATERALLY SPACED PARALLEL WATER-COOLED PIPES, TWOWATER-COOLED HEADERS SEVERALLY SECURED TO THE OPPOSITE ENDS OF SAIDPIPES, A WATER-COOLED JACK VERTICALLY SUPPORTING EACH HEADER,WATER-COOLED LATERAL BRACES EXTENDING OUTWARDLY FROM THE OPPOSITE SIDESOF EACH HEADER, A ROW OF CLOSELY ARRANGED REFRACTORY BLOCKS HAVINGLOAD-BEARING PORTIONS SEATED ON SAID PAIR OF PIPES BETWEEN SAID HEADERS,AND REFRACTORY RAIL ELEMENTS BORNE BY SAID BLOCKS FOR SLIDEABLYSUPPORTING THE METAL ARTICLES TO BE HEATED IN SAID FURNACE.